In industrial robot, it is necessary to arrange cables inside the machine body, to thereby supply operating elements such as a robot arm, robot wrist and end-effector with electric power, electric signals, pressurized air, and work-assisting gas and the like. For example, U.S. Pat. No. 4,540,332 discloses a system for arranging cables by which damage to the cables is prevented. The cable arrangement system disclosed in U.S. Pat. No. 4,540,332, however, is not designed to hold a plurality of cables within the robot body by a cable holding means, and to distribute the cables.
The conventional cable arrangement within the rotational trunk applicable to the laser robot employs a cable arrangement system as shown in FIGS. 7 through 9B. Namely, as can be clearly seen from FIGS. 7, 8A, and 8B, to retain the lower cable group, two support metal plates 91 are provided, each of which is inwardly horizontally extended from one of the apertures 1a and 1b at both sides of the robot base 1, and metal clamps 92 each having a cable holding portion with a rectangular section are fixed to the end of each support plate 91, to thereby hold two groups of cables 7a and 7b, respectively. Then the two groups of cables 7a and 7b are tied to form a single cable bundle 7c at the center, and are led upward. Next, as shown in FIGS. 7, 9A, and 9B, the cable bundle 7c extending upward from an interior of the robot base 1 to an interior of the rotational trunk 2 (.theta. designates a rotational direction about the vertical axis), is arranged so as to pass through the space between the ends of two support metal plate 93 each extending from windows 21a, 21b at both sides of the rotational trunk 2, to the center thereof. Clamps 94 formed from metal plate having a rectangular section are then fastened to the respective support plates 93 arranged face to face to thereby hold therein, respective, one each of the half bundles of the bundle cable 7c, as best shown in FIG. 9B.
As clearly understood from the above description, in the conventional cable arrangement system, the cable bundle 7c extends upward from the interior of the robot base 1 along the rotational axis of the robot rotatable trunk 2 within the industrial robot, and therefore, the conventional laser robot incorporating such a cable arrangement system employs a structure in which an outer laser beam conduit 96 extends from a laser oscillator 95 located outside, to reach a position in register with the rotational axis of the rotatable trunk 2 via a beam conduit support 97 mounted on the upper part of the robot machine body, as shown in FIGS. 10A and 10B.
The system for arranging the cable bundle 7c described above requires much cumbersome work when assembling the support plates 93, in which the cable 7c extending along the rotational axis is taken out through the trunk window 21a and 21b, retained by the clamps 94 outside the robot machine body, lead back into the rotational trunk 2 together with the support plates 93, and the two support plates 93 are fixed in the vicinity of the window 21a and 21b provided on the side of the rotational trunk 2. As a result, the cable arrangement work and the cable maintenance work requires an extraordinary amount of labor and time.
Further, since a laser beam conduit of the laser robot is supported by the beam conduit support 97 mounted on the upper part of the robot, such a beam conduit support 97 necessarily restricts a range of movement of the robot. Further, when the laser beam enters the robot from a top thereof, the outer laser beam conduit 96 must be arranged above the robot, and various parts and members needed to support the conduit must be provided in the vicinity of the robot machine body, and thus the arrangement of the peripheral equipment and the like in the region of the robot is restricted.
Also, since the laser beam can be introduced only from overhead, only the two methods shown in FIGS. 10A and 10B are applicable, i.e., the method in which the laser beam is introduced from overhead of a laser robot placed on the floor, and the method in which the robot base is mounted on the ceiling in such a way that the robot machine body is extended down toward the floor, and the laser beam is introduced from the top of the rotatable trunk.